A pileup involving 50 to 60 vehicles during a spring snow squall in Pennsylvania on Monday killed at least three people and caused multiple injuries, officials said.

Part of Interstate 81 about 100 miles northwest of Philadelphia was closed until further notice. Authorities said Tuesday that clean-up was “about half done” and urged motorists to avoid the area.

At least 20 people were transported to hospitals, Schuylkill County Emergency Management said. Three people died, said John Mika of the Schuylkill County Coroner’s Office.

A collision involving as many as 40 vehicles closed part of Interstate 81 in Pennsylvania on Monday, authorities say.WBREA collision involving as many as 40 vehicles closed a portion of Interstate 81 in Pennsylvania on Monday, according to the Schuylkill County Office of Emergency Management.A collision on I-81 in Pennsylvania on Monday.WBREA collision involving as many as 40 vehicles closed a portion of Interstate 81 in Pennsylvania on Monday, according to the Schuylkill County Office of Emergency Management.A collision on I-81 in Pennsylvania on Monday.WBRE

Fire rescue teams, Pennsylvania State Police and state Transportation Department staff members responded to the scene between exits 116 and 119. 

State police said a large fire involving several vehicles was burning.

It’s unclear what caused the pileup. Low visibility due to the late-season snowstorm appeared to have contributed.

March 29, 202203:45

Video showed vehicles that had been pulled to the side of the road being hit by traffic as heavy fog covered the interstate. Large black smoke plumes rose from what appeared to be a vehicle on fire, based on video taken by someone who said they were involved in the crash after they got out of their car.